Radar sensors are frequently used to acquire the environment surrounding the radar sensor. If the radar sensor is situated on a vehicle, for example the surrounding environment of the vehicle is acquired. For this purpose, the radar sensor sends out electromagnetic waves having specific wave parameters such as frequency and/or modulation. The emitted electromagnetic waves are reflected by external objects that may be present in the surrounding environment of the radar sensor. A portion of the reflected electromagnetic waves is received by the receive antennas, and is then evaluated.
Typically, runtime differences, expressed for example as one or more phase relations between adjacent receive antennas, are measured. Thanks to a known speed of propagation of the electromagnetic waves, in this way the direction of an external object on which the emitted electromagnetic waves have been reflected can be determined (so-called directional or angular estimation).
Frequently, such radar sensors are installed inside a larger object, for example a vehicle, for example behind a bumper of the vehicle. When there is a partial reflection of electromagnetic waves from a bearer of the receive antennas to the bumper, a new reflection of the electromagnetic waves from the bumper back to the receive antennas can take place. This effect can occur several times in succession.
The electromagnetic waves, reflected to the receive antennas once or multiple times, are superposed with the original electromagnetic waves reflected only at the external object. If a runtime difference between different receive antennas, representing different receive channels, is now evaluated, then portions of the undesired single or multiple reflections are also taken into account in the evaluation.
German Patent Application No. DE 10 2013 221 091 A1 describes a radar mounting system integrated in a bumper for use in a vehicle.